The present invention relates to a system for measuring three-dimensional coordinates by tracking a free curved surface using a noncontact-type displacement measuring instrument such as an optical sensor, a magnetic sensor, or the like.
FIG. 1 shows a conventional three-dimensional measuring system using a noncontact-type sensor, wherein reference numeral 1 denotes a linear scale for detecting the positions of Cartesian coordinates of three axes, i.e., X-axis, Y-axis and Z-axis, 20 denotes a noncontact-type sensor that instantaneously reacts when it is brought into contact with the surface to be measured in any direction of X-axis, Y-axis or Z-axis, and 50 denotes a computer system for filing the three-dimensional coordinates.
The operation will be described hereinbelow. The contact-type sensor (hereinafter referred to as probe) 20 produces a signal instantaneously when it is held by hand and is brought into contact with the surface of an object that is to be measured. The signal is sent to the computer 50. Namely, the computer receives the coordinate data at that moment from the linear sensor and files it.
According to the conventional three-dimensional measuring apparatus constructed as described above, the measurement could be taken by simply bringing the probe into contact with points from where the measurement was to be taken. Therefore, when a curved surface S is to be measured from a point A to a point B as shown in FIG. 2, the operator judges corner points on the curved surface and brings the probe into contact therewith to take the measurement. To grasp the data of the curved surface, however, a number of points must be measured as indicated by N.sub.1 to N.sub.10 in FIG. 2. When a high degree of precision is required, therefore, the measurement must be taken involving tremendously laborious work.